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Speech Codecs and Associated PSQM Values

The following test sets were run using VOCAL ATA’s with different speech files and network load conditions. The results provide a general indication of the relative performance of the PSQM algorithm in ranking the performance of different speech codecs under various conditions. For further information on the exact test conditions and to discuss your voice application requirements, please contact us directly.

PSQM

PSQM is a computational and modeling algorithm defined in International Telecommunications Union Recommendation ITU-T P.861 (1996) that objectively evaluates and quantifies voice quality of voice-band (300Hz – 3400 Hz) speech codecs.

PSQM uses psychoacoustical mathematical modeling to analyze the pre and post transmitted voice signals. It yields a PSQM value which is measures signal quality degradation and ranges from 0 (no degradation) to 6.5 (highest degradation). In turn, PSQM values translate into a Mean Opinion Score (MOS), which is an accepted measure of the perceived quality of received media ranging from 1 to 5. A value of 1 indicates unacceptable, poor quality voice while a value of 5 indicates high voice quality with no perceptible issues.

Test Set 1

 

Ideal Conditions: No Network Load with Artificial Voice
G.711u G.711a G.726 32kbps G.729a G.723.1 iLBC GSM AMR 12.2kbps Speex
MOS AVG
(PSQM)
4.45 4.44 4.3 4.04 4.08 4.1 4.14 3.84

 

Test Set 2

 

Ideal Conditions: No Network Load with Both Gender Voice
G.711u G.711a G.726 32kbps G.729a G.723.1 iLBC GSM AMR 12.2kbps Speex
MOS AVG
(PSQM)
4.3 4.29 4.21 3.76 3.74 3.81 3.96 3.78

 

Test Set 3

 

Normal Conditions: 1% Packet Loss with Both Gender Voice
G.711u G.711a G.726 32kbps G.729a G.723.1 iLBC GSM AMR 12.2kbps Speex
MOS AVG
(PSQM)
4.24 4.25 4.14 3.74 3.75 3.82 3.94 3.79

 

Test Set 4

 

Duress: 5% Packet Loss with Both Gender Voice
G.711u G.711a G.726 32kbps G.729a G.723.1 iLBC GSM AMR 12.2kbps Speex
MOS AVG
(PSQM)
4.13 4.11 3.79 3.51 3.57 3.74 3.79 3.59

 

VOCAL Technologies, Ltd.
520 Lee Entrance, Suite 202
Amherst New York 14228
Phone: +1-716-688-4675
Fax: +1-716-639-0713
Email: sales@vocal.com